1. Field of the Invention
The present invention relates to a semiconductor device including a capacitor element.
2. Description of Related Art
As the recent trend is shifting toward compact and lightweight electronic devices operable with high speeds and high frequency, there is an increasing demand to raise an integration degree of a semiconductor integrated circuit. Similarly, a higher capacitance per unit area than ever before has been required of a capacitor element mounted to the semiconductor integrated circuit.
As a capacitor element for an integrated circuit, proposed are a capacitor element structured such that parallel plates forming upper and lower electrodes sandwich a dielectric, and a comb-like capacitor element realized by improving upon the above one so as to form a capacitance between multilayer lines (see Japanese Patent Translation Publication No. 2003-530699 and Japanese Unexamined Patent Publication No. 11-168182, for example).
FIG. 15 is an upper view showing the structure of the capacitor element disclosed in Japanese Patent Translation Publication No. 2003-530699, and FIG. 16 is a perspective sectional view of the capacitor element of FIG. 15. In a capacitor element 104, as shown in FIGS. 15 and 16, plural wiring layers (e.g., a first layer line 111, a second layer line 112, a third layer line 113, and a fourth layer line 114) are laminated on a substrate 131 made of a semiconductor material, lines of the respective wiring layers laminated on the substrate 131 are arranged to alternately form different electrodes (first electrode A and second electrode B) as shown in FIG. 16. A space between the wiring layers and a space between the lines forming the wiring layers are filled with a dielectric (not shown). Along the direction vertical to the substrate 131, the lines of the same electrode are arranged, and the lines of the respective layers (respective layer lines) are electrically connected together through first via holes 121 or second via holes 122 to constitute one vertical plate. The vertical plate forms an electrode of the capacitor element.
FIG. 17 is a perspective view showing the structure of the capacitor element disclosed in Japanese Unexamined Patent Publication No. 11-168182, FIG. 18A is an upper view of the capacitor element of FIG. 17, and FIG. 18B is a sectional view taken along the line IV-IV of FIG. 18A. As shown in FIG. 17, in a capacitor element 105, plural wiring layers (for example, a first layer line 111a, a second layer line 112a, and a third layer line 113a) are laminated on a substrate 131a made of a semiconductor material, and lines of the respective wiring layers laminated on the substrate 131a are arranged to alternately form different electrodes (first electrode A and second electrode B) as shown in FIG. 17. A space between the wiring layers and a space between lines forming the respective wiring layers are filled with a dielectric (not shown) as in the related art. Along the direction vertical to the substrate 131a, the lines of different electrodes are alternately arranged. As shown in FIG. 18A, first via holes 121a and second via holes 122a for connecting between different wiring layers of the same electrode are formed at one ends of the lines. Besides, Japanese Unexamined Patent Publication No. 11-168182 discloses such a capacitor element that the line of the second layer line 112a is arranged orthogonally to the first layer line 111a and third layer line 113a. 
The total capacitance of the capacitor element disclosed in Japanese Patent Translation Publication No. 2003-530699 is the sum of the total crossover capacitance between the vertical plates, and the total fringe capacitance between plural combined vertical plates. Further, the total capacitance of the capacitor element disclosed in Japanese Unexamined Patent Publication No. 11-168182 is the sum of the capacitance between adjacent lines of different electrodes arranged in the direction horizontal to the substrate, the capacitance between adjacent lines of different electrodes arranged in the vertical direction, the capacitance of the line forming the second electrode that is close and opposite to the first via hole at one end of the line, the capacitance of the line forming the first electrode that is close and opposite to the second via hole at one end of the line, and the total fringe capacitance. The use of such capacitor elements enables higher capacitance density than the conventional comb-like capacitor element.
Thus, there has been a strong demand for the technique capable of making the most of a high integration process, and increasing a capacitance per unit area.